How can I achieve this "security camera" effect?
Switching a camera is pretty easy with the Scene Actuator in "Set Camera" mode.

Switching controls/behavior is independent from the camera, as it has no relation to what is rendered. Typically you "enable" a set of controls while you "disable" another set of controls.

There are many ways to achieve this effect. The basic idea is that each entity remembers if it is enabled or disabled (= state) and acts accordingly.

Additionally you need a way to request one or multiple state changes e.g. via property change, message listening or other events.

Example:
When receiving message "enable security camera", you 


let the camera switch to the security camera, 
disable the current controls on the player's avatar
enable the controls on the security camera
...


When receiving message "enable security camera", you 


let the camera switch to the player's camera, 
disable the controls on the security camera
enable the controls on the player's avatar
...


if you have a lot of such objects and possible toggles, you might want do this is two steps:


disable all
enable what was requested


This way you do not care the previous state.